Diagnosis of Respiratory Disease

Diagnosis of Respiratory Disease

Diagnosis of a respiratory disease involves a combination of clinical evaluation, pulmonary function tests, and imaging. A healthcare provider will start with a physical exam and medical history, followed by tests like spirometry to assess lung function, and imaging techniques such as chest X-rays, CT scans, or MRIs to visualize the lungs and identify structural abnormalities. Other tests can include arterial blood gas tests or pulse oximetry to check oxygen and carbon dioxide levels. 

Clinical evaluation

• Medical history and symptoms: The doctor will ask about your symptoms, duration, triggers, and family history of respiratory conditions.
• Physical exam: This includes listening to your lungs with a stethoscope for abnormal sounds like wheezing or crackling, and checking your vital signs. 

Pulmonary function tests (PFTs) 

• Spirometry: Measures the volume and speed of air you inhale and exhale to assess how well your lungs are working.
• Peak flow meter: A device used to measure how fast you can exhale, which can be used at home for monitoring.
• Arterial blood gas (ABG): A blood test to measure the amount of oxygen and carbon dioxide in your blood.
• Pulse oximetry: A sensor is clipped onto your finger to non-invasively measure the oxygen saturation in your blood. 

Imaging studies

• Chest X-ray: Provides a 2D image of your lungs and chest cavity to detect issues like pneumonia or tumors.
• CT (Computed Tomography) scan: Offers more detailed cross-sectional images than a standard X-ray, useful for conditions like emphysema.
• MRI (Magnetic Resonance Imaging) scan: Uses magnets and radio waves for detailed images of soft tissues.
• PET (Positron Emission Tomography) scan: Can help identify and diagnose lung cancer by highlighting cancerous cells. 

Diagnosis of Upper Respiratory Tract Disease

Diagnosis of an upper respiratory tract disease typically starts with a doctor’s medical history and a physical exam. For more specific identification of the pathogen, especially in complex cases or to rule out infections like influenza or RSV, rapid antigen tests or PCR assays may be used, while throat or nasal swabs and cultures are also common diagnostic tools. 

Initial assessment

• Medical history: The doctor will ask about your symptoms, how long you’ve had them, and any potential exposure to sick individuals.
• Physical examination: A physical exam will likely include checking your ears, nose, throat, and lungs, and listening to your breathing. 

Laboratory and other tests

• Throat or nasal swab: A swab can be taken to check for specific bacteria or viruses.
• Rapid antigen tests: These can provide results in 15-30 minutes for viruses like influenza, RSV, and SARS-CoV-2.
• PCR (Polymerase Chain Reaction): This is a more sensitive and specific test that can identify viral pathogens and is often used in complex cases or for hospitalized patients.
• Viral culture: This involves collecting a sample (like a throat swab) to grow and identify viruses. It can take longer than rapid tests.
• Chest X-ray: May be ordered for severe or persistent symptoms to rule out conditions like pneumonia.
• Blood tests: A complete blood count (CBC) or other blood tests may be conducted in more serious cases.
• Antibody titers: This involves taking two blood samples at different times to compare antibody levels, which can help diagnose a past viral infection. 

When to see a doctor

You should see a doctor if you experience symptoms like a high or prolonged fever, difficulty breathing, a persistent cough, severe sore throat, or ear pain. 

Diagnosis of Lower Respiratory Tract Disease

Diagnosis of lower respiratory tract disease begins with a medical history and physical exam, followed by imaging and lab tests. Key diagnostic steps include using a stethoscope to listen to the lungs, performing pulse oximetry to measure blood oxygen levels, conducting a chest X-ray or CT scan, and analyzing sputum and blood samples. Additional tests like spirometry or a bronchoscopy may be ordered for more detailed analysis. 

Initial assessment

• Medical History: A doctor will ask about your symptoms, their duration, and onset.
• Physical Exam: The doctor will perform a physical examination and listen to your lungs with a stethoscope to check for abnormal breath sounds. 

Diagnostic tests

• Pulse Oximetry: A sensor attached to the finger or ear measures the amount of oxygen in your blood.
• Chest X-ray or CT Scan: These imaging tests create a picture of your lungs to look for signs of infection, inflammation, or other abnormalities.
• Blood Tests: Blood is drawn to check for signs of infection or inflammation and to identify bacteria or viruses.
• Sputum Culture: A sample of mucus is collected and sent to a lab to identify the specific bacteria or viruses causing the infection.
• Spirometry: This test measures how much air you can inhale and exhale and how quickly you can exhale.
• Bronchoscopy: For more persistent or chronic conditions, a flexible tube with a camera is inserted into the airways to visualize them and collect a tissue sample.
• Tuberculin Skin Test: This test can be used to check for tuberculosis.
• Arterial Blood Gas: This is a blood test that provides detailed information about oxygen and carbon dioxide levels in your blood. 

Common Diseases of Upper Respiratory Tract

Common upper respiratory tract diseases include the common cold, influenza, sinusitis, pharyngitis, and laryngitis. These are typically viral or bacterial infections affecting the nasal passages, sinuses, throat, and voice box, and they usually present with symptoms like congestion, sore throat, and cough. 

Common Diseases

• Common cold (nasopharyngitis): A viral infection that is the most frequent type of upper respiratory tract infection (URTI), caused by numerous viruses, especially rhinovirus.
• Influenza (Flu): A viral infection with symptoms that can be more severe than the common cold, often including high fever, headaches, and body aches.
• Sinusitis (sinus infection): Inflammation of the sinuses, often a complication of a cold, which can be caused by viral, bacterial, or fungal infections.
• Pharyngitis (sore throat): An inflammation of the pharynx, commonly known as a sore throat, which can be viral or bacterial (e.g., strep throat).
• Laryngitis: An inflammation of the larynx (voice box) that causes hoarseness and can be triggered by an URTI.
• Tonsillitis: Inflammation of the tonsils, a common form of pharyngitis. 

Less Common but Serious Conditions

• Epiglottitis: A serious and potentially life-threatening condition involving inflammation of the epiglottis.
• Croup: An infection, usually viral, that causes a distinctive barking cough, inflammation of the larynx and trachea, and is more common in young children.
• Whooping cough (Pertussis): A highly contagious bacterial infection causing severe coughing fits. 

Common Diseases of Lower Respiratory Tract

Common lower respiratory tract diseases include pneumonia, acute bronchitis, influenza, and bronchiolitis. These are often caused by viruses or bacteria and can lead to serious health complications, especially in vulnerable populations like young children, the elderly, or those with weakened immune systems. Asthma and chronic obstructive pulmonary disease (COPD) are other common chronic lower respiratory diseases. 

Common infectious diseases

• Pneumonia: An infection of the lung’s air sacs (alveoli) that can be caused by bacteria, viruses, or fungi. Symptoms include fever, chills, cough, and difficulty breathing.
• Acute Bronchitis: A short-term infection of the bronchial tubes, often caused by viruses. Symptoms include a cough that can bring up mucus. In people with underlying lung conditions like COPD, it can be more severe.
• Bronchiolitis: An infection of the small airways, most often affecting infants and young children under two years old, frequently caused by viruses like RSV. It is a common cause of hospitalization for infants.
• Influenza: A viral infection that can affect the lower respiratory tract, causing symptoms like fever, cough, and fatigue. 

Common chronic diseases

• Asthma: A chronic condition where the airways become inflamed and narrowed, leading to wheezing, coughing, and shortness of breath.
• Chronic Obstructive Pulmonary Disease (COPD): A group of lung diseases that block airflow and make it difficult to breathe, with chronic bronchitis being one type. 

Medical History Taking for Upper Respiratory Tract Disease

To take a history for an Upper Respiratory Tract Disease, start with the presenting complaint and explore its characteristics, including cough, sore throat, nasal congestion, and fever. Ask about associated symptoms like headaches, ear pain, and shortness of breath, as well as risk factors such as recent contacts, travel, allergies, and smoking history. A thorough history includes past medical and respiratory history, current medications, and family history of similar conditions. 

Presenting complaint 

• Symptoms: What are the specific symptoms? (e.g., sore throat, cough, nasal congestion, runny nose, headache, fever)
• Duration: When did the symptoms start? How long have they lasted?
• Severity: How severe are the symptoms on a scale?
• Progression: How have the symptoms changed over time? 

History of the presenting complaint 

• Cough:
  • Characteristics: Is it productive (bringing up sputum) or non-productive? What color is the sputum?
  • Timing: Is it worse at certain times of day?
  • Associated symptoms: Is there any blood in the sputum? Are there coughing fits (paroxysms)?
• Sore throat: Where is the pain located? Does it radiate to the ear?
• Nasal symptoms: Describe the nasal congestion and discharge. Is there pain or pressure in the face or around the eyes?
• Fever: What is the temperature? Is it accompanied by chills or rigor?
• Other symptoms:
  • Headache or facial/dental pain
  • Ear pain or a feeling of fullness
  • Hoarseness
  • Shortness of breath (dyspnea)
  • Malaise, body aches (myalgias), or fatigue 

Past and relevant history

• Past medical history: Have you had similar symptoms before? Do you have a history of other respiratory illnesses like asthma or COPD?
• Allergies: Are you allergic to any medications, pollen, or other environmental factors?
• Medications: Are you currently taking any medications? Did you take anything for this illness?
• Vaccinations: Are your immunizations up to date? 

Social and environmental history

• Contacts: Have you been in contact with anyone who has been ill?
• Exposure: Are there any recent exposures at daycare, school, work, or home?
• Travel: Have you traveled recently?
• Lifestyle: Do you smoke? Have you been exposed to any occupational hazards? 

Family history

• Does anyone in your family have a history of similar illnesses or chronic respiratory diseases? 

Physical Examination for Upper Respiratory Tract Disease

A physical exam for upper respiratory disease involves examining the nose, throat, and ears, as well as listening to the lungs. Key steps include checking vital signs, inspecting the throat for redness or exudates, and using an otoscope to check the ears for signs of infection. The chest is auscultated to listen for abnormal lung sounds like crackles or wheezes, and the neck is palpated for swollen lymph nodes. 

Head and neck exam 

• Throat: Inspect for redness (erythema), pus (exudates), or swelling of the tonsils (tonsillar hypertrophy).
• Ears: Use an otoscope to look inside the ear canal for signs of infection (otitis).
• Neck: Gently feel for enlarged lymph nodes (adenopathy) in the neck.
• Nose: Inspect for discharge, noting if it is clear or thick and discolored. 

Chest exam 

• Inspection: Observe for symmetry in chest movement, signs of labored breathing (using accessory muscles), and any abnormalities in the chest shape.
• Auscultation: Listen to the lungs with a stethoscope for abnormal sounds like:
  • Crackles: Popping sounds, often indicating fluid in the lungs.
  • Rhonchi: Low-pitched, coarse sounds.
  • Wheezes: High-pitched, whistling sounds, which can suggest airway constriction.
• Palpation: Feel the chest for tenderness or abnormal vibrations.
• Percussion: Tap on the chest to assess the underlying tissue, which can help identify fluid or air pockets. 

Other components

• Vital signs: Take the patient’s temperature, pulse, and respiratory rate, as a fever or rapid heart rate can indicate an infection.
• General appearance: Note if the patient looks anxious, is in discomfort, or has difficulty speaking full sentences without pausing to breathe.
• Skin and nails: Look for signs like pallor or cyanosis (bluish discoloration), which can indicate anemia or low oxygen levels. Finger clubbing (swelling of the fingertips) is a sign of chronic lung disease, not typically an acute upper respiratory infection. 

Spirometry Pulmonary Function Test

Spirometry is a common pulmonary function test that measures how much and how fast you can exhale air from your lungs. It is used to diagnose and monitor lung conditions like asthma and COPD, and involves taking a deep breath and blowing out as hard and fast as possible into a device. The test helps assess how well your lungs are working by measuring metrics such as forced vital capacity (FVC) and forced expiratory volume in the first second (FEV1). 

What happens during the test

• You will be asked to sit upright and wear a clip on your nose so you can only breathe through your mouth.
• You will take a deep, full breath in.
• You will then exhale as forcefully and as completely as possible for as long as you can.
• The spirometer device measures your breathing effort.
• The test may be repeated several times to ensure accurate results. 

Why spirometry is performed

• To diagnose lung diseases: It can help diagnose conditions such as asthma, COPD, emphysema, and pulmonary fibrosis.
• To monitor lung function: It is used to track the progression of a lung disease or to check how well medications are working.
• To evaluate pre-operative risk: It can determine if your lungs are functioning well enough for a planned surgery.
• For occupational screening: It may be used to screen for lung disorders related to your job. 

Potential risks and side effects

• Spirometry is generally a safe test, but the physical exertion can cause temporary dizziness, light-headedness, or fatigue.
• Some people may experience coughing, chest tightness, or a brief increase in heart rate.
• It is not recommended for individuals who have recently had a heart attack or have certain heart conditions.
• Tell the technician if you feel any discomfort during the test. 

Laboratory Test for Throat and Nasal Swab

Throat and nasal swabs are common methods for collecting samples to diagnose respiratory infections caused by viruses, bacteria, or fungi. The samples are sent to a laboratory for testing using techniques like cultures or molecular assays to identify the specific pathogen. 

Common Uses

• Throat Swab (Culture): Primarily used to diagnose conditions like strep throat (Group A Streptococcus bacteria), scarlet fever, abscesses, or pneumonia. It can also detect fungal infections like thrush.
• Nasal Swab: Used to test for a variety of respiratory viruses and bacteria, including:
  • Influenza (the flu)
  • COVID-19
  • Respiratory Syncytial Virus (RSV)
  • Whooping cough (Bordetella pertussis)
  • Meningitis
  • MRSA (methicillin-resistant Staphylococcus aureus).
• Combination Swab: In some cases, and with specific test kits, a combination of both a throat and nasal swab is used, which can increase the detection rate for certain viruses, such as some SARS-CoV-2 variants. 

Test Procedure

The collection process is quick and can cause a brief tickling, gagging, or the urge to sneeze, but is generally painless. 

• Throat: A healthcare provider uses a sterile cotton swab to gently rub the back of the throat and tonsil areas, avoiding the tongue and cheeks to prevent contamination.
• Nasal: A swab is inserted into the nostril and rotated against the nasal wall for several seconds to collect a sample. This may be done on one or both sides, depending on the test type (e.g., anterior nares, mid-turbinate, or nasopharyngeal). A nasopharyngeal swab goes deeper into the nose to the upper part of the throat and is typically performed by a healthcare professional. 

Laboratory Analysis

Once collected, the sample is sent to a lab for analysis. Common laboratory methods include: 

• Culture: The sample is placed on a special plate to allow bacteria or fungi to grow over a few days, after which they can be identified and tested for antibiotic sensitivity.
• Rapid Antigen Test: This test can detect specific viral or bacterial proteins (antigens) in minutes.
• Molecular Assays (e.g., PCR, NAAT): These tests detect the genetic material (DNA or RNA) of the pathogen. They are highly accurate and are often the preferred method for diagnosing certain infections, though results may take longer than a rapid test. 

The test results help healthcare providers determine the best course of treatment, such as prescribing appropriate antibiotics or antiviral medications.